1. Field of the Invention
The present invention relates to a damper apparatus for controlling the flow of air which is supplied into an oven cavity in a machinery compartment of a microwave oven and, more particularly, to a damper apparatus for a microwave oven in which the structure of the damper apparatus is simplified to thereby reduce the production cost and obtain the reliability of the operations at the same time.
2. Description of the Prior Art
A microwave oven is an apparatus in which microwave is generated by applying current, the thusly generated microwave is introduced into an oven cavity, a space for accepting a heating object, for thereby heating the heating object.
Such a microwave oven has various functions due to the diversification of required heating characteristics. For instance, a product having a heater for heating food at a higher temperature therein is developed.
The microwave oven having such a heater is advantageous because it can have more various heating characteristics compared to conventional microwave ovens, escaping from a single heating characteristic utilizing microwave.
That is, it is possible to heat food at a higher temperature and brown the surface of food using an electric heater.
And, the microwave oven forms an air flow for exhausting steam or smoke generated by heating, in the cavity which is a space for heating.
FIG. 1 is a perspective view illustrating a general microwave oven which is divided into a cavity (C), a space for heating food by a partition 11, which is opened or closed by a door 12, and a machinery compartment 10 which has a microwave generating unit for generating microwaves.
The machinery compartment 10 includes a high voltage transformer 13 for boosting a supplied current to a high voltage, a magnetron 14 for oscillating microwave using a high voltage supplied by the high voltage transformer 13, a cooling assembly 20 for radiating the high voltage transformer 13 and the magnetron 14 which generate much heat when driving the microwave oven, an air duct 15 which allows a part of cooling air generated in the cooling assembly 20 to cool the high voltage transformer 13 and the magnetron 14 to thereafter introduce the same into the cavity (C).
Herein, the path through which the part of cooling air is introduced into the cavity will be described as follows.
The cooling air generated in the cooling assembly 20 is guided through the air duct 15 installed adjacent to the magnetron 14, and introduced into the cavity (C) through a plurality of air vents(not shown) formed on the partition 11 which partitions between the cavity (C) and the machinery compartment 10.
That is, the partition 11 corresponding to the inside of the air duct 15 has an inlet port including a plurality of air vents(not shown) formed thereon, and the cooling air guided through the air duct 15 is introduced into the cavity through the inlet port.
And, the thusly introduced cooling air is exhausted to the outside of the microwave oven through an outlet port(not shown) formed on the opposite wall of the cavity, along with steam or smoke generated in the cavity (C).
In the microwave oven having a heater(not shown) thus described, when heating food using the heater(not shown), the cavity (C) in which the food is placed has a very high temperature, and heat of such a high temperature gradually heats the food.
By such a heating operation using the heater, food is heated by itself, or at the same time using microwave oscillated by the magnetron 14.
In the case that food has to be heated at a high temperature as described above, it is not preferred that the cooling air from the cooling assembly 20 is introduced into the cavity (C).
That is, when the cooling air of a low temperature is introduced into the cavity and exhausted to the outside, the loss of heat is actually large.
Thus, the cooling air of a low temperature must be selectively introduced into the cavity (C) through the air duct 15. As an example of the above-described construction, U.S. Pat. No. 4,450,344 will be described as follows with reference to FIG. 2.
FIG. 2 is a block diagram illustrating the construction of a conventional damper apparatus for a microwave oven. As shown therein, the cooling air from the cooling fan assembly 20 can be selectively introduced into the cavity (C) by allowing a damper 30 to open or close the inlet port 16 which is a path into the cavity (C).
More specifically, the damper apparatus includes a cam member 40 to which the rotation of a motor 41 is transferred; a damper link 31 which is eccentrically connected to the cam member 40; a damper 30 for opening or closing the inlet port 16 in which one end 30a is connected to the damper link 31, and the other end is rotatably connected to one side of the partition 11; and a micro switch which is installed at one side of the cam member 40 for thereby detecting the rotation volume of the cam member 40.
The operation mode of the thusly constructed damper apparatus is as follows. The rotation of the motor 41 is transferred to the cam member 40 for rotation purposes, the damper 30 is interlocked with the damper link 31 which is connected to the cam member 40, thereby opening or closing the inlet port 16, and the open state and the close state are detected by the micro switch 50 for sensing the rotation volume of cam member 40
However, the above-described damper apparatus has problems that the mechanical elements for transferring the rotation of the motor (M) to the damper 30 are complicated so that the production unit price is increased and the assembly characteristics are deteriorated.
In addition, since the micro switch 50 for detecting whether the damper opens or closes the inlet port 16 is constructed to contact the cam member 40 for thereby detecting the open and close states of the damper by sensing the rotation angle thereof, the micro switch 50 cannot directly detect the damper 30. Thus, there arises another problem that it is difficult to detect the full-open state of the damper 30 due to the clearances between the complex elements or the combination of assembly allowances.
Furthermore, there is still another problem that because it is difficult for the damper to fully open or close the inlet port, a gap is generated and thus a cooling air is introduced.
Accordingly, it is an object of the present invention to provide a damper apparatus for a microwave oven in which a rotation shaft of a damper and a rotation shaft of a driving motor are formed in one united body in order to simplify the damper and its peripheral construction and control the damper accurately.
To achieve the above object, there is provided a damper apparatus for a microwave oven which includes an air duct for guiding a cooling air from the machinery compartment of the oven into the cavity; a damper rotatably installed in the air duct for opening or closing the flow of air in the air duct; a motor which includes a shaft directly connected to the damper to thereby drive the damper; and a micro switch installed at one side of the air duct for detecting the opening and closing states of the damper by contacting one side of the damper.
Additional advantages, objects and features of the invention will become more apparent from the description which follows.